Field of the Invention
The invention relates to a method for producing silicon carbide monocrystals.
Metal smelting processes, silicon melting processes, and cultivation processes through the gas phase are known for producing cubic silicon carbide monocrystals. The best results have been obtained thus far by cultivation using the sublimation process. In that process, silicon carbide (SiC) in solid form is sublimated and grown as a silicon carbide monocrystal through the gas phase on a seed crystal or seed crystal. However, in a sublimation process, temperatures of over 2000.degree. C. as a rule have to be handled.
A method for growing SiC out of an aqueous solution at room temperature is knows from Japanese Patent JP 57042600. In that known method, however, the growth rates are extremely low.
A publication entitled: Journal of Crystal Growth, Vol. 53 (1981), p. 542, discloses a hydrothermal process for cultivating quartz crystals, in which quartz at temperatures between 350.degree. C. and 500.degree. C. is dissolved in a KCl or NaCl solution in a pressure-proof autoclave and crystallizes out of the solution on a seed.
A publication entitled: Diamond and Related Materials, Vol. 4 (1995), pp. 234-235 discloses a hydrothermal process for cultivating diamond crystals, in which a special aqueous solution is placed in a pressure-proof autoclave, and a polycrystalline diamond film is grown out of the solution on a diamond seed crystal, at a temperature of 400.degree. C. and a pressure of 170 MPa.
A review of other known hydrothermal syntheses is provided in a publication entitled: Angewandte Chemie [Applied Chemistry], Vol. 97, 1985, pp. 1017-1032.